458 research outputs found

    Three-body structure of the low-lying 17^{17}Ne-states

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    The Borromean nucleus 17^{17}Ne (15^{15}O+p+p + p + p) is investigated by using the hyperspheric adiabatic expansion for a a three-body system. The measured size of 15^{15}O and the low-lying resonances of 16^{16}F (15^{15}O+p + p) are first used as constraints to determine both central and spin-dependent two-body interactions. Then, the ground state structure of 17^{17}Ne is found to be an almost equal mixture of s2s^2 and d2d^2 proton-15^{15}O relative states, the two lowest excited states have about 80% of sdsd-mixed components, and for the next two excited three-body states the proton-15^{15}O relative s-states do not contribute. The spatial extension is as in ordinary nuclei. The widths of the resonances are estimated by the WKB transmission through the adiabatic potentials and found in agreement with the established experimental limits. We compare with experimental information and previous works.Comment: 29 pages, 7 postscript figures, to be published in Nuclear Physics

    Anatomy of three-body decay III. Energy distributions

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    We address the problem of calculating momentum distributions of particles emerging from the three-body decay of a many-body resonance. We show that these distributions are determined by the asymptotics of the coordinate-space complex-energy wave-function of the resonance. We use the hyperspherical adiabatic expansion method where all lengths are proportional to the hyperradius. The structures of the resonances are related to different decay mechanisms. For direct decay all inter-particle distances increase proportional to the hyperradius at intermediate and large distances. Sequential three-body decay proceeds via spatially confined quasi-stationary two-body configurations. Then two particles remain close while the third moves away. The wave function may contain mixtures which produce coherence effects at small distances, but the energy distributions can still be added incoherently. Two-neutron halos are discussed in details and illustrated by the 2+2^+ resonance in 6^{6}He. The dynamic evolution of the decay process is discussed.Comment: 30 pages, 8 figures, to be published in Nuclear Physics

    Breakup Reactions of 11Li within a Three-Body Model

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    We use a three-body model to investigate breakup reactions of 11Li (n+n+9Li) on a light target. The interaction parameters are constrained by known properties of the two-body subsystems, the 11Li binding energy and fragmentation data. The remaining degrees of freedom are discussed. The projectile-target interactions are described by phenomenological optical potentials. The model predicts dependence on beam energy and target, differences between longitudinal and transverse momentum distributions and provides absolute values for all computed differential cross sections. We give an almost complete series of observables and compare with corresponding measurements. Remarkably good agreement is obtained. The relative neutron-9Li p-wave content is about 40%. A p-resonance, consistent with measurements at about 0.5 MeV of width about 0.4 MeV, seems to be necessary. The widths of the momentum distributions are insensitive to target and beam energy with a tendency to increase towards lower energies. The transverse momentum distributions are broader than the longitudinal due to the diffraction process. The absolute values of the cross sections follow the neutron-target cross sections and increase strongly for beam energies decreasing below 100 MeV/u.Comment: 19 pages, 14 figures, RevTeX, psfig.st

    Three-body Faddeev Calculation for 11Li with Separable Potentials

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    The halo nucleus 11^{11}Li is treated as a three-body system consisting of an inert core of 9^{9}Li plus two valence neutrons. The Faddeev equations are solved using separable potentials to describe the two-body interactions, corresponding in the n-9^{9}Li subsystem to a p1/2_{1/2} resonance plus a virtual s-wave state. The experimental 11^{11}Li energy is taken as input and the 9^{9}Li transverse momentum distribution in 11^{11}Li is studied.Comment: 6 pages, RevTeX, 1 figur

    Single-Proton Removal Reaction Study of 16B

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    The low-lying level structure of the unbound system 16^{16}B has been investigated via single-proton removal from a 35 MeV/nucleon 17^{17}C beam. The coincident detection of the beam velocity 15^{15}B fragment and neutron allowed the relative energy of the in-flight decay of 16^{16}B to be reconstructed. The resulting spectrum exhibited a narrow peak some 85 keV above threshold. It is argued that this feature corresponds to a very narrow (Γâ‰Ș\Gamma \ll 100 keV) resonance, or an unresolved multiplet, with a dominant π(p3/2)−1⊗Μ(d5/23)J=3/2+\pi (p_{3/2})^{-1} \otimes \nu (d_{5/2}^3)_{J=3/2^+} + π(p3/2)−1⊗Μ(d5/22,s1/2)J=3/2+\pi (p_{3/2})^{-1} \otimes \nu (d_{5/2}^2,s_{1/2})_{J=3/2^+} configuration which decays by d-wave neutron emission.Comment: 16 pages, 5 figures, 1 table, submitted to Phys. Lett.

    Particle-unstable nuclei in the Hartree-Fock theory

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    Ground state energies and decay widths of particle unstable nuclei are calculated within the Hartree-Fock approximation by performing a complex scaling of the many-body Hamiltonian. Through this transformation, the wave functions of the resonant states become square integrable. The method is implemented with Skyrme effective interactions. Several Skyrme parametrizations are tested on four unstable nuclei: 10He, 12O, 26O and 28O.Comment: 5 pages, LaTeX, submitted to Phys. Rev. Let

    Psychology research in women’s soccer: a scoping review

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    Previous research suggests that psychological factors play an important role in trying to explain and predict the participation, performance, and health of player and practitioners in soccer. However, most previous works have focused on specific research questions and included samples from male populations. As part of a larger FĂ©dĂ©ration Internationale de Football Association (FIFA) project aiming to steer women’s soccer research, our purpose with this scoping review was to give an overview of the current state of psychology-related research within women’s soccer. We searched five electronic databases up to April 2023, from which 280 original peer-reviewed articles met the inclusion criteria. Included records were inductively coded into 75 specific research topics and nine broader research categories. Population characteristics within each topic and category, and overall publication trends, were identified. The results revealed a growth in research attention, with notable increases in publication rates around the international competitions years, over the last two decades. While a notable number of abstracts did not report sufficient details about population age and/or playing levels, senior elite players were identified as the most common population studied. Most studies examined several topics from different research categories, with research focusing on emotions, moods and/or environmental factors, and the specific the topics of anxiety, stress, and coach behavior, receiving most research attention. Our study provides an informative mapping of all psychology-related research activity within women’s soccer, which will enhance researchers’ understanding of the current quantity of literature within this complex, heterogeneous, and growing area of research

    Complex population structure and haplotype patterns in the Western European honey bee from sequencing a large panel of haploid drones:Sequencing haploid honey bee drones

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    International audienceHoney bee subspecies originate from specific geographical areas in Africa, Europe and the Middle East, and beekeepers interested in specific phenotypes have imported genetic material to regions outside of the bees' original range for use either in pure lines or controlled crosses. Moreover, imported drones are present in the environment and mate naturally with queens from the local subspecies. The resulting admixture complicates population genetics analyses, and population stratification can be a major problem for association studies. To better understand Western European honey bee populations, we produced a whole genome sequence and single nucleotide polymorphism (SNP) genotype data set from 870 haploid drones and demonstrate its utility for the identification of nine genetic backgrounds and various degrees of admixture in a subset of 629 samples. Five backgrounds identified correspond to subspecies, two to isolated populations on islands and two to managed populations. We also highlight several large haplotype blocks, some of which coincide with the position of centromeres. The largest is 3.6 Mb long and represents 21% of chromosome 11, with two major haplotypes corresponding to the two dominant genetic backgrounds identified. This large naturally phased data set is available as a single vcf file that can now serve as a reference for subsequent populations genomics studies in the honey bee, such as (i) selecting individuals of verified homogeneous genetic backgrounds as references, (ii) imputing genotypes from a lower-density data set generated by an SNP-chip or by low-pass sequencing, or (iii) selecting SNPs compatible with the requirements of genotyping chips

    Complex population structure and haplotype patterns in the Western European honey bee from sequencing a large panel of haploid drones

    Get PDF
    Honey bee subspecies originate from specific geographical areas in Africa, Europe and the Middle East, and beekeepers interested in specific phenotypes have imported genetic material to regions outside of the bees' original range for use either in pure lines or controlled crosses. Moreover, imported drones are present in the environment and mate naturally with queens from the local subspecies. The resulting admixture complicates population genetics analyses, and population stratification can be a major problem for association studies. To better understand Western European honey bee populations, we produced a whole genome sequence and single nucleotide polymorphism (SNP) genotype data set from 870 haploid drones and demonstrate its utility for the identification of nine genetic backgrounds and various degrees of admixture in a subset of 629 samples. Five backgrounds identified correspond to subspecies, two to isolated populations on islands and two to managed populations. We also highlight several large haplotype blocks, some of which coincide with the position of centromeres. The largest is 3.6 Mb long and represents 21% of chromosome 11, with two major haplotypes corresponding to the two dominant genetic backgrounds identified. This large naturally phased data set is available as a single vcf file that can now serve as a reference for subsequent populations genomics studies in the honey bee, such as (i) selecting individuals of verified homogeneous genetic backgrounds as references, (ii) imputing genotypes from a lower-density data set generated by an SNP-chip or by low-pass sequencing, or (iii) selecting SNPs compatible with the requirements of genotyping chips.This work was performed in collaboration with the GeT platform, Toulouse (France), a partner of the National Infrastructure France Génomique, thanks to support by the Commissariat aux Grands Invetissements (ANR-10-INBS-0009). Bioinformatics analyses were performed on the GenoToul Bioinfo computer cluster. This work was funded by a grant from the INRA Département de Génétique Animale (INRA Animal Genetics division) and by the SeqApiPop programme, funded by the FranceAgriMer grant 14-21-AT. We thank John Kefuss for helpful discussions. We thank Andrew Abrahams for providing honey bee samples from Colonsay (Scotland), the Association Conservatoire de l'Abeille Noire Bretonne (ACANB) for samples from Ouessant (France), CETA de Savoie for sample from Savoie, ADAPI for samples from Porquerolles and all beekeepers and bee breeders who kindly participated in this study by providing samples from their colonies.info:eu-repo/semantics/publishedVersio
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